Mercury nitrate as a reagent for the preparation of nitrophenols



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TENNEY L. DAVIS, OF SQMERVILLE, TEASSACHUSETTS.

MERCURY NITRATE AS A REAGENT FOR- TI-IE PREPARATION. 0J5 NITROPHENOLS.

No Drawing.

Specification of Letters Patent. Patented hiay 23, 1922.. Application filed April-16,1921. Serial No. 4=62,029.

(FILED UNDER THE ACT OF MARCH 3, 1883, 22 STAT. 1]., 625.)

T 0 all whom it may concern:

Be it known that I, TnNNn-Y l1. DAVIS, a citizen of the United States, and a resident State of Massachusetts, have invented an Improvement in Mercury Nitrate as a, Re agent "for the lreparation ot- Nitrophenols, of which the following is a specification.

The invention described herein may be used by the Government, or any of its ot'ticcrs or employees in prosecution of work for the Government, or by any other person in the l nited States, without payment to me of any royalty thereon.

.The subject ot-this invention is mercury nitrate as a reagent for the preparation of nitrophenols. The main objects of the invention are a more absolute control of the process for the production of nitrophcnols and an increase in the yield of nitrophenols.

it is well known to chemists that nitric acid, alone or in the presence of sulphuric acid. acting on aromatic compounds yields nitro dcrivativ-es. Thus, benzene. treated with nitric acid alone or with a nitric-sulphuric acid mixture yields nitro-benzene "for the first product. It is-also well known that nitric acid acting on aromatic substances in the presence of mercury nitrate yields, in addition to the usual nitro derivative, a certain amount of the nitro-hydroxyl or nitrophenolic compounds. Thus, benzene treated with nitric acid in the presence of mercury nitrate yields nitro-benzene and dinitrophenol. This second substance is converted by further treatment with nitric acid into picric acid or trinitrophenol; and the process of treating benzene with nitric acid in the presence of mercury nitrate has been used "for the technical preparation of picric acid.

reason that it has been supposed that the mercury salt acts catalytically and by presence, in some way facilitating the oxidation by the nitric acid of the hydrogen atom of the aromatic nucleus to an hydroxyl group. Slnce it has been supposed that the mercury ,salt acts catalytic-ally, a small quantity of it of Somerville, county of Middlesex, and

I have discovered that the mercury salt in such reactions does not function as a catalyser but as a real re-agent which enters into the chemical reaction. I have found that the larger the amount of mercury salt which is used the greater is the yield of nitrophenol. By treating nitrobenzene, 1.3 dinitrobenzene, 1.3.5 trinitrobenzene, and 2&6 trinitrotoluene for several hours with hot strong nitric acid in the presence of a molecular equivalent of mercury nitrate. l have adequately demonstrated that the presence of mercury salt does not facilitate the oxidation by means of nitric acid of the hydrogen atom of the aromatic nucleus. In the case of nitrobenzene some nitration oc' curs, and, along with the nitrobenzene which was recovered there was obtained a considerable quantity o l 1.3 dinitrobenzene. In the case of the other three substances. the original material was recovered unchanged in practically theoretical amount. Trinitrobenzene and trinitrotoluene are readily oxidized by as gentle and oxidizing agent as aqueous potassium ierricyanide, yielding respectively picric acid and trinitrocresole, yet in my experiments they were unattached by prolonged treatment with nitric acid at a boiling temperature in the presence of mercury nitrate. 'lrinitrotohn one is oxidized by hot nitric-sulplniric acid mixture. or more readily by chromic acid in sulphuric acid solution, to yield trinitrobenzoic acid. As none of this substance was produced in my experiments, it is apparent that mercury nitrate does not act cat-alytically and by presence to facilitate the oxidizing action of nitric acid whether this oxidizing agent is conceived as acting on the hydrogen of the aromatic nucleus or on the hydrogen of the side-chain.

I have discovered that nitric acid and mercury nitrate acting on benzene in the cold produce a complex compound which I have isolated in the term of a black solid. This solid is soluble in nitric acid. Treated with hot nitric acid it reacts with it to form oxide of nitrogen, mercury nitrate, and 2.4 'linitrophenol or picric acid ac carding to the conditions of reaction. The forv mation of this complex compound requires a molecular'proportion of mercury, and the nitrate acts as a real reagent in the process.

' tro-fn-chlorphenol 'from they do not at the same time The knowledge that it does so makes it possible to'carry out the first step of the reaction under conditions which lead exclusively to the formation of the complex compound and so avoid the formation of simple nitro derivatives,'like nitrobenzene; and to carryout the second step of the process under conditions which decompose the compicx compound into a nitrophenol while produce its destructive oxidation by the nitric acid.

By this process I have prepared 2.4 dinitrophenoland picric acid from benzene, trinitro-m-cresole from toluene, and trinichlorbenzene. I

find that/sulphuric acid interferes with the process, perhaps because it leads to the forclaim as new and desire to secure by Letters Patent, is:

1. The process of producing nitrophenols, comprising treatin an aromatic compound withnitricacid and mercury nitrate to produce a complex compound and then decomposing the complex compound with nitric acid into nitrophenolt 2. The process of producing nitrophenols, comprising treating an aromatic compound, using a mercury salt as a re-agent, to produce a complex compound and then decomposing, the complex compound with nitric acid into nitrophenol.

' TENNEY L. DAVIS. 

